Drafting-instrument



(No Model.)

0. R. HOWARD.r

DRAFTING INSTRUMENT.

Patented N0v.1,1881.-

ATTORNEYS.

u. Punks Phmummpbef. washing uA cA NTTE STATES PATENT OEErcE.

OYRUS lt. HOWARD, OF HUNTINGDON, PENNSYLVANIA.

DRAFTlNG-INSTRUMENT.

SPECIFICATION forming part of Letters Patent No. 249,049, dated November 1, 1881.

4 Application IiledAugust 5,1881. (No model.)

To all whom it may concern Be it known that I, CYRUS R. HOWARD, of Huntingdon, in the county of Huntingdon and State of Pennsylvania, have invented an Improved Drafting-Instrument, ot' which the following is a specification.

The object of my invention is to furnish an instrumentfor marking out geometrical figures; and it consists in the combination of a markingarm, a post carrying numerous figure-plates, and an adjustable ringer carried by the marking-arm for engagement with either ligureplate, as hereinafter described and claimed.

In the accompanying drawings, Figure lis a side elevation of the instrument in the position of use. Fig. 2 is a top view of the same. Fig. 3 is a cross-section on line .fc x of Fig. l. Fig. 4 is a longitudinal section ou line yy of Fig. 3. Fig. 5 is a plan view ot' the foot-piece, and Figs. 6 and I are face views of gure-plates.

Similar letters of reference indicate corresponding parts.

A is the post ot' the instrument, and B is the pencil or scribin g arm, hinged to a short horizontal arm, a, that is fitted to turn on the upper end of post A. l

Oisahollowcylinder,havingremovablcheads b b, through which the upper end of post A passes, so that the cylinder is supported on the post between a collar, c, and cross-pin c', and may turn freely. Within the cylinder and on the post are the figure-plates d, which 4may be as numerous as desired, and are separated by washers c, that are or" larger diameter than the plates, so as to l'orm grooves around the several plates. The shaft is squared andthe plates are apertnred to correspond, so that they may not turn. The plates d vary in shape, as shown in Figs. 3, 6, and 7, and may be ot' any desired shape-such as circular, square, oval, rhomboidal, octagonal, hexagonal, &c.

Len gthwise of cylinder C is a screw, f,which is held in place bythe heads b b, and hasahead, j", on its upper end for convenience in turning thescrew. At one side of the cylinder, and outside the same, there are two xevd rods, g g, on which is a slide-block, h, that has a flange portion, h', extending through a slot, g', in the cylinder to the screwj'. The flange is threaded to receive the screw, so that by turning the latter the block h is moved on the rods g.

The pencil-arm B has a slot in which is a curved arm, fi, held to the arm by a set-screw, k. To the inner end of arm 'i is pivoted a finger, l, that extends through the slide-block h and the slot g ofthe cylinder to the figure-plates d. A spring, m, attached to block h and engaging the finger l, tends to retain the finger in contact with the ligure-plate at which it is set. This construction allows, first, adjustment ot' arm B on the curved arm t', whereby the size of the ligure inscribed is regulated, and, second, adjustment of block l1, so that the ringer Z shall engage either ot' the ligure-plates d. To adjust block h, the arms A B must be stretched apart far enough to release the ringer l from the washers-e and the screw f, then turned until the block is in the proper position, when the arms are to be released,and the spring m will carry the finger into place. l

The lower end of post A is formed angular, and a foot-piece, D, formed to receive the end of the post, is provided for sustaining it. On the foot-piece are sharp prongs o, which, being caused to en ter the surface on which the piece is laid, prevent the piece D and postfrom turning.

In use the post A is placed in the foot-piece l) and the cylinder O turned by hand, while the pencil rests on the surface to be marked. The arm B is thus carried around the post, and at the same time is caused to move in and out by the nger l, according to the form of the ligure-plate, so that the form of the gureplate is produced on an enlarged scale.

As shown in Fig. 1, the cylinder C is marked adjacent to the slot g,lwith lines that correspond in position with the ligure-plates d, and the lines are numbered or otherwise marked to indicate the figures. The block h has a pointer which serves, in connection with the lines, to aid the adjustment of block h.

Having thus described my invention, l claim as new and desire to secure by Letters Patent- 1. The combination,inadrafting-nstrument, of a post carrying figure-plates, a pencil-arm hung to revolve on the post, and a nger hung on the pencil-arm and engaging either figureh, provided with nut h, finger l., spring m, arm to plate on the post, substantially as shown and 1',tixed post A,carrying plates d,and the markdescribed. ing-arm B, substantially as shown and de- 2. The combination,inadrafting-instrument, scribed7 combined for operation as set forth.

of post A, provided with figure-plates d marking-arm B, slotted cylinder C, slide harm i, OYRUS R HOWARD and finger l, substantially as shown and de- Witnesses:

scribed. T. W. MONTGOMERY,

3. In draftin g-instruxnents, the screw f, slide J. OLIVER CUNNINGHAM. 

